It doesn't seem like there is. mozilla.debian.net says:
>Jessie and Stretch backports of Firefox release and beta are gone because of the requirement of rust to build them, which is not available in Jessie or Stretch. Please update your apt sources to use Firefox ESR instead.
I've downloaded the tarball from the firefox homepage, extracted it, and put it in ~/opt, and symlinked it to ~/bin/firefox, which is on my path first.
>Jessie and Stretch backports of Firefox release and beta are gone because of the requirement of rust to build them, which is not available in Jessie or Stretch. Please update your apt sources to use Firefox ESR instead.
I've downloaded the tarball from the firefox homepage, extracted it, and put it in ~/opt, and symlinked it to ~/bin/firefox, which is on my path first.